Does it Really? Reality and Ertrick say it better then me, but a "Fetch Quest" is a Meaningless Task to that usually has Little to nothing to do with the Gameplay. Usually an Item for an NPC, a Good Example of this being the Biggoron Sword in Ocarina of Time.
Collect-athons Differ because the Items you Collect have everything to do with the Gameplay. Usually Having something to do with using the Character's Abilities to Explore and Fight Obstacles in your way.
I know im not going to Convince you, As I always Say, You do You.